What does it mean to have hard or soft water? Learners discover the chemistry behind water hardness in the fifth video of a seven-part series describing our water resources. Using simple animations and balanced chemical equations, young environmental chemists uncover the mystery of why soap is far less bubbly in hard water. To finish, the video includes a discussion of rain's classification as soft water.

Concepts

water, groundwater, rain, sediment, limestone, calcium, calcium carbonate, soap, hardness

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Additional Tags

science

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Instructional Ideas

• Set up a demonstration of soap in hard and in soft water prior to viewing the resource
• Have lab partners design an experiment they could use to test water hardness at school or home

Classroom Considerations

• Pupils need some prior knowledge of the chemistry of carbonates and hydrophilic/hydrophobic molecules 

Pros

• Illustrates the process by which water becomes hard using correct terms and balanced equations—perfect for reinforcing both vocabulary and the importance of balancing
• Animated scenes show how once-soft rain water becomes hardened in its trip through the water table

Cons

• None